Automatic seat borer



1967 A. J. BROUlLLETT E 3,297,066

AUTOMATIC SEAT BORER Filed Dec. 28, 1964 5 Sheets-Sheet 1 FIG! AUTOFFNEYS Jan. 10, 1967 A. J. BROUILLETTE 3,297,066

AUTOMATIC SEAT BORER Filed D60. 28, 1964 3 Sheets-$heet 2 FIGZ WW9. @Wm

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ATTORNEKS 1967 A. J. BROUILLETTE 3, 9

AUTOMATIC SEAT BORER Filed Dec. 28, 1964 I5 Sheets-Sheet 5 H66 W W A TTD/PNEYS United States Patent 3,297,066 AUTQMATIQ SEAT BURER Aihert .l'. Erouillette, Winchendon, Mass, assignor to Heywood-Wakefield Company, Gardner, Mass, a corporatior: of Massachusetts Filed Dec. 28, 1964, Ser. No. 421,199 3 Claims. ((1 144--l10) This invention relates generally to automatic boring machines and, more particularly, to a machine for automatically boring the holes required in the top and bottom of a seat blank for a wooden chair to prepare the seat bottom for receiving the rails of the back and arm structure on one side and the supporting legs on the other side.

Boring of wooden seat blanks for the construction of conventional wooden chairs having four supporting legs and a back and arm structure that may involve ten or more wooden spindles presents many difficult problems. The principal problem is the obtaining of accurate alignment for the direction in which the holes are drilled into the seat blank in order that the legs and back structure of the chairs, with or without arms as the case may be, will all have a proper angular relationship and be readily assembled in subsequent operations. Since the seat blank generally has a top surface saddle contour, there is very little flat surface from which a reference for angular measurement can be made; and except for the members on the center line of the chair, the reference for such angular measurements in two perpendicular planes is not readily defined. A second difiiculty associated with boring seat blanks is the closeness of the spacing of the holes, particularly for the back spindles where spacings of approximately two inches are common.

In the past in order to drill seat blanks of this type, a power transmission empolying two or more universal joints has been used to drive each drill bit with the angular position of the drilling axis set individually and by hand as the boring machine is set up to drill a particular style of chair bottom. These universal joint power transmissions have a severe limitation on the angle of approach that can be accommodated; and if this angle, which is approximately seventeen degrees, is exceeded, the universal joints suffer from an inordinately high breakage rate. This factor results in a particular seat bottom requiring two or more set-ups to achieve drilling of all the holes required, i.e. the seat blank must be set under the drilling fixture in two or three or more successive drilling positions in order that the universal joint power transmissions can drill into the seat blank within acceptable angular ranges to avoid breakage of the universal joint transmission. By the nature of the close spacing of the holes required for the back spindles, individual electric motor drives for each drill bit are precluded; and the choice of a mechanical transmission is severely limited by the physical closeness of the adjacent parts required to drill the holes. Obviously multiple set up requirements and successive operations on the single seat blank greatly increase the cost of manufacture of the seat blank and limit the production rate by the factor involved in the multiple set-up operations.

Previous boring machines suffer from other limitations which have been completely overcome in the present automatic machine. In particular, the previous arrangements for boring a seat blank made no provision for flattening the blank so that the location and the angularity of the holes drilled in the blank would be precise with reference to a planar reference surface on the blank. Thus if a warped seat blank were drilled by the old method, the spacing and the angular relation of the holes would be in error; and the subsequent assembly of the spindles and 3,2973% Patented Jan. 1W, 1W6? legs to the erroneously positioned holes would produce a skewed effect in the assembled spindle back and leg assembly so that the chair would sit unevenly or present a definite skewed or warped appearance in the spindle back. Furthermore, since chairs are produced in relatively small production runs, it was necessary to change the machine set-up periodically and re-establish all the drilling angle-s each time a production run on a particular chair style was desired. This was generally accomplished by employing a sample drilled seat bottom which served as a master blank with the mechanic establishing the angular adjustment of the drilling axes of the bits by the actual insertion of the bit into the drilled hole in the master blank. This procedure results in errors due to the gradual enlargement of the holes in the master blank with the consequent ambiguity as to the correct angular adjustment for the individual drill bits. As previously stated, since the angular relationship of a set of holes in a chair blank is a relatively complex one, the manual adjustment of these on repeated runs shows little consistency in achieving the correct angular relation and hence c0nsequent assembly operations of the legs, arms and spindle back elements is subject to all the difficulties previously mentioned with respect to angularly drilled holes in warped blanks.

The present invention provides an automatic machine which overcomes all of the disadvantages set forth above in connection with prior art seat blank boring machines and further makes provision for manufacturing any desired number of different chair seat bottoms on an interchangeable basis with only a single drilling operation required per seat bottom and a minimum of set-up time when production runs for different types of seat bottoms are to be made. In the normal operation of a large furniture manufacturer the machine thus improves the productive capacity both by eliminating multiple set-up for the individual seat bottoms as they have the required number of holes drilled therein and the extensive length of time required to change from one style chair to another which normally required, in the past, the adjustment of each drilling bit. In addition, the subsequent manufacturing operations can be carried on at an accelerated pace and with a great reduction in the reject rate by virtue of the accuracy with which the holes are drilled in the seat blank to accept the spindle and leg assembly without warping or skewing from the normally artistic and functionally controlled positions required of these elements. Since the seat blank is bored in a clamped flat position, the subsequent assembly of these elements maintains the seat blank in this flat position due to the re-enforcing truss effect of the elements assembled to the seat blank, thereby giving a greater degree of uniformity and style fidelity to the production run.

The foregoing objects and advantages of the present invention will be apparent from the following detailed description taken in conjunction with the accompanying drawings wherein:

FIG. 1 is a side view in perspective of the complete automatic boring machine showing a seat bl-ank before drilling;

FIG. 2 is a perspective view of the machine from the operators position showing the seat blank after being drilled;

FIG. 3 is a fragmentary sectional view taken along the line 33 of FIG. 2;

FIG. 4 is a perspective view of a typical type of seat blank drilled by the present machine;

FIG. 5 is a View in perspective of the top plate portion of the master template of the machine;

FIG. 6 is a perspective view of an interchangeable back spindle drilling template for the machine; and

FIG. 7 is a side elevation view of one of the automatic drilling units and its supporting template.

Referring now to the drawings, the general assembly of the complete machine will be described. FIGS. 1 and 2 show a massive table leg support structure 11 which provides an open top support frame 12 for a master template assembly 13. The master template 13 rests directly on cross members at the top of the leg assembly 11 and consists of a heavy steel top plate 14, a heavy steel bottom plate 15 and vertical spacing supports 16 holding the master template assembly 1446 in assembled relation as a rectangular parallelepiped fastened with recessed Allenhead machine screws. The outer surfaces of the assembled plates 14 and 15 provide for mounting the drilling templates as hereinafter described.

The spacing between the top plate 14 and the bottom plate 15 is adequate for the insertion and Withdrawal of a seat blank 17 which is the work-piece to be drilled by the machine. To enable accurate location of the seat blank 17 inside the master template 13, a forward stop 18 and a side stop 19 are provided against which the seat blank 17 is urged by the operator in order that each blank may assume the same relative position with respect to the machine.

As best seen in FIG. 3, a vertical bracket 21 is secured to the outer surface of top plate 14 for supporting a pneumatic linear actuator 22 which operates through a hole 23 in the top plate 14 to depress a clamping bar 24 inside the master template 13 which substantially spans the width of the chair blank 17. The purpose of the clamping bar 24 and the actuator 22 is to supply sufficient clamping pressure to the blank 17 to bring the bottom surface of the blank 17 into intimate engagement with the planar surface of the bottom plate 15. The actuator 22 applies suflicient force to produce this result even though the blank may he somewhat warped. For the purpose of applying this force, the bar 24 is of a length to span the scooped out saddle portion of the top surface of the seat blank 17 and may, if desired, have a protective rubberized finish or other surface layer for protecting the finish of the work-piece 17.

Secured to the outer surface of top plate 14 of the master template is a back template 31 (shown in detail in FIG. 6) consisting of a flat plate 32 having a crescentshaped edge 33 and on which are securely mounted a plurality of pedestal supports 34. The pedestals 34 are machined with an accurate planar bottom surface with the appropriate angular inclination to support the pedestal 34 at the desired angle when secured to the planar surface 32. For this purpose machine screws may be passed through appropriately positioned countersunk holes in the plate 32 upwardly into threaded holes in the bottom surface of the pedestals 34. The location and angular orientation of the pedestals 34 on the plate 32 is a highly precise machining and assembly operation; and this assembled relation of the pedestals 34 and the plate 32 determines the spacing between the back spindles and their inclination, both with respect to the vertical and with respect to each other. It will be noted that except for the centrally located pedestals, the angle at which each pedestal 34- rests on the plate 32 is inclined with respect to two mutually perpendicular planes taken as a co-ordinate system reference perpendicular to the horizontal bottom surface of the chair blank when the template is in assembled position as shown in FIGS. 1 and 2. Thus the actual angle of the pedestals 34 will, in general, be a compound angle made up of the resultant of the two mutually perpendicular angles in the aforesaid reference co-ordinate planes. It is the fact that this angle is compound and has two components with respect to the ordinary reference co-ordinates of the chair and the fact that there is no convenient way to measure these angles that makes the template 31 contribute significantly to the time saved in setup operations for drilling a particular chair seat and the accuracy with which the resultant set of drilled holes is obtained.

The assembled back template 31 of FIG. 6 is secured to the outer surface of the top plate 14 of the master template assembly as shown in FIGS. 1 and 2 by means of machine screws projecting downwardly through countersunk holes 30 in the plate 32 into threaded holes 65 in the plate 14. By this means the relative position of the plate 32 on the plate 14 is controlled and the interchangeable templates 31 for different chair seats can determine the actual location as well as the angular inclination of the holes drilled in the seat blank 17 by virtue of the precision location accuracy of the drilled holes for the securing screws in the plates 14 and 32.

Each of the pedestals 34 has a key-way slot 35 in its front face and supports thereon a T-bracket 36 which has an apertured internally-threaded projection 37 for supporting a drilling unit 38. The drilling units 38 are preferably Ingersoll-Rand heavy duty Rapid Automatic Drill units which operate from a pneumatic air supply of approximately pounds line pressure supplied by a single rubber hose 39. The drill units 38 have a characteristic of turning the bit to drill a hole and advancing the chuck and drill to an adjustable predetermined depth so that when the hole has been drilled to the predetermined depth, the chuck retracts, withdrawing the drill from the drilled hole and in the retracted position shuts the unit off. With such drill units no problem is presented in feeding the drill or retracting the drill from the drilled hole so that the chair blank 17 can be positioned in its proper location without any attention by the operator in assuring that the bits have been retracted from the work area between the plates 14 and 15.

The drill units 38 have a threaded end 41 which engages the internally threaded holes in apertured plates 37 of the T-brackets 36 thereby accurately and securely fixing the drill units 38 in the position determined by the location of the T-bracke-ts 36. The T-brackets 36 include a key-way mating with the key-way 35 on the pedestals 34 and an appropriately shaped key is positioned in the matingkey-ways to keep the brackets 36 and pedestals 34 accurately aligned.

With the template 31 assembled on the master template top plate 14, the drills 38 are positioned to project through a crescent shaped slot 42 in the plate 14 which is large enough to permit the extended chuck-s to drive the respective bits into the chair blank 17. The slot 42 is oversize to accommodate the entire range of drill spacings encountered in the interchangeable set of templates 31.

Where a chair blank for a chair having side arms is being drilled, appropriate arm support spindles will be required; and for this purpose arm holes are drilled in the blank 17 by a pair of drill actuators 38 mounted in separate arm pedestals 44, 45.

As best seen in FIG. 3, the bottom plate 15 has secured to the outer surface thereof a pair of leg templates 51, 52, each supporting a pair of spaced pedestals 53 having appropriate T-brackets 54 for supporting drill units 38 as previously described for the top template 31. The templates 51 and 52 are accurately positioned to the outer surface of the bottom plate 15 of the master template assembly 13 by means of accurately positioned threaded holes in the under surface of the plate 15 which receive machine screws (not shown) that are recessed into the under surface of the templates 51 and 52 and pass therethrough to secure the templates 51 and 52 accurately to the outer surface of the plate 15. In this manner, by merely interchanging two templates 51 and 52, any desired range of leg positions and angles can be achieved for different chair styles; and for this purpose the plate 15 has four oversize holes (not shown) located to receive the range of leg bore hole positions required for the entire product line which is to be manufactured by the machine.

FIG. 4 shows a seat blank 17 having a saddle scooped out portion s1 with a back spindle array of holes 63 drilled therein and two arm support holes 64 drilled therein. This entire array of holes plus four leg holes (not shown) on the under surface. are drilled simultaneously in a single actuation of the machine with the task being accomplished in the order of ten to twenty seconds depending on the hardness of the wood, the grain density, sharpness of the bits and general power capability of the drill units 38.

PEG. 5 shows the top plate 14 of the template assembly 13 and includes the holes 65 for securing the interchang able template 32 thereto by means of machine screws passing downward-1y through the holes 30 which are recessed in the top surface of the plate 32 to permit the heads of the screws to be flush with the top surface. Similarly, the arm template pedestals 44 and 45 are secured in predetermined position on the plate 14 by means of machine screws passing through holes 66 and 67. The plate 14 has the oversize crescent-shaped slot 42 for the back spindle drills and also has holes 68 which are sulficiently oversize to permit the projection of the bit and drill unit therethr-ough for the full positional range of the arm supports in the chairs being manufactured on the machine.

FIG. 6 shows the general appearance of the interchangeable type back spindle templates 31 which are used with the machine, a number of which are supplied for the purpose of drilling the individual back spindle arrays of the different machines being manufactured. For any particular chair style, one template 31 will be selected corresponding to the back spindle array for that chair; and the unit selected corresponding to FIG. 6 is bolted in place on the top plate 14 for completely determining the position and angle of each of the drill units 38 required for that particular chair. As indicated in FTG. 7, the angle of the pedestal 34 with respect to the horizontal determines the drilling angle of bit 71 with respect to the horizontal and the same can be said with respect to the vertical plane through the center line of the boring axis. In other words, the angle of the drill 71 in the plane normal to the paper will be determined by the angle that the pedestal 34 has with respect to the plane normal to the plane of the figure. In this manner an accurate compound angle for the drilling axis of the bit 71 can be obtained with respect to a conventional Cartesian co-ordi nate system.

Any desired automatic or semi-automatic control system can be employed for operating the machine. In the disclosed embodiment, a foot pedal actuated valve unit 71 is arranged on the floor convenient to the operators osition for actuating the linear actuator 22. The valve unit 71 is preferably of the type which will alternately extend and retract the actuator 22 upon successive actuations of the foot pedal.

The pneumatic pressure to energize the drill units 38 is supplied from a pair of manifolds 72 which are supplied pressure from two interlocked hand-operated valves 73. The pair of valves 73 assure the operator of having both hands clear from the interior of the template 13 when the drills are actuated in order to avoid the possibility of personal injury to the operator. The manifold 72 may be provided with pressure gauges 74, if desired, to visual ly check on the operating air pressure available to the drill units 38.

The operation of the machine will be apparent from the foregoing description and may be briefly summarized as follows. The operator stands facing the machine in the position shown in FIG. 2 and inserts the seat blank 17 against the stops 18 and 19. The operator actuates the pedal valve 71 and the linear actuator 22 extends to press the clamping bar 24 against the seat blank 17 to securely clamp it against the bot-tom plate and straighten any warped condition the blank 17 may have. The operator places both hands on the valves 73 and depresses both valves to charge the manifolds 72 and upon predetermined pressure being attained all of the drill units 38 start their drilling cycle. As previously stated, the drilling cycle of the units 38 rotates the bits, extends the chuck to a predetermined depth after which the chuck is retracted to its normal position and the rotative motion is stopped. Thus, once the cycle has started, the drills will run until each drill has drilled a hole of predetermined depth in the blank 17 and the drill has been withdrawn and rotation stopped. This operation in general will not take the same time for each drill unit 38 since the holes drilled are of different size and depth and the different portions of seat blank 17 have different hardness due to the grain structure of the wood. After all the drilling has been completed, the operator actuates the pedal valve 71 again to retract the actuator 22 thereby unclamping the blank 17 so that it can be readily withdrawn.

While the machine has been described with reference to the normal top and bottom position of the seat blank as the chair would be used, it will be apparent that the description describing portions of the machine as being top or bottom portions, as used herein, refers to the top surfiace and bottom surface of the seat blank. Accordingly, the use of these terms in the specification and claims should not be construed as precluding construction of the machine in other orientations with respect to the vertical.

Many other modifications will be likewise apparent in view of the present disclosure and the invention should be construed as limited only by the scope of the appended claims.

I claim:

1. A chair seat boring machine for simultaneously boring holes in the top and bottom surfaces of a seat blank comprising:

a master template having spaced parallel top and bottom supporting plates with said bottom plate apertured for four leg hole drills and said top plate apertured for a set of back spindle drills;

a back spindle template removably secured to the outer surface of said top plate, said back spindle template having an array of drill support pedestals thereon with the spatial and angular relation of the back spindles for a particular chair seat blank and a pneumatic drill actuator mounted on each of said ped estals, said actuators each operable to rotate, drive to a predetermined depth and retract a drill bit mounted therein on a boring axis parallel to the axis of its respective mounting pedestal;

leg template means removably secured to the outer surface of said bottom plate and supporting four leg pedestals having the spatial and angular relation of the legs for said chair seat blank, each of said leg pedestals supporting a pneumatic drill. actuator similar to said actuators on said back spindle template;

a transverse clamping bar between said top and bottom plates extending substantially the width of said seat blank;

an actuator on said top plate coupled to drive said clamping bar toward said bottom plate and positioning said clamping bar to avoid interference with the drill travel of any holes bored in the top surface of said seat blank;

positioning means for locating a seat blank in predeteriined position between said top and bottom plates of said master template; and

means operable to energize said actuator to clamp said seat blank securely against the inner surface of said bottom plate and subsequently energize all of said drill actuators to bore all of the holes in the top and bottom of said seat blank, retract said drills and finally retract said clamping bar to permit removal of the drilled seat blank.

2. Apparatus according to claim 1 in which said top plate has a pair of holes located to include a range of arm support hole locations in said seat blank and including a pair of arm templates removably secured to the outer surface of said top plate With drill support pedestals thereon having the spatial and angular relation of arm supports for said seat blank, and pneumatic drill actuators mounted on said pedestals on said arm templates and connected to be actuated with the other drill actuators to drill holes for arm supports in the top surface of said seat blank.

3. Apparatus according to claim 1 in which said pedestals on said back template are metal posts of square crosssection With a Width substantially equal to the transverse dimension of said pneumatic drill units to permit minimum spacings and Wide latitude in the convergence angle between adjacent drilled holes and the bottom of each of said posts being planar with a compound angle relative to a square end to give each post when mounted on the base of said back template the same angular inclination as desired for the hole drilled by the drill unit mounted on said post.

References Cited by the Examiner UNITED STATES PATENTS 3,189,065 6/1965 Cochrane et al. 144-94 DONALD R. SCHRAN, Primary Examiner. 

1. A CHAIR SEAT BORING MACHINE FOR SIMULATANEOUSLY BORING HOLES IN THE TOP AND BOTTOM SURFACES OF A SEAT BLANK COMPRISING: A MASTER TEMPLATE HAVING SPACED PARALLEL TOP AND BOTTOM SUPPORTING PLATES WITH SAID BOTTOM PLATE APERTURED FOR FOUR LEG HOLE DRILLS AND SAID TOP PLATE APERTURED FOR A SET OF BACK SPINDLE DRILLS; A BACK SPINDLE TEMPLATE REMOVABLY SECURED TO THE OUTER SURFACE OF SAID TOP PLATE, SAID BACK SPINDLE TEMPLATE HAVING AN ARRAY OF DRILL SUPPORT PEDESTALS THEREON WITH THE SPATIAL AND ANGULAR RELATION OF THE BACK SPINDLES FOR A PARTICULAR CHAIR SEAT BLANK AND A PNEUMATIC DRILL ACTUATOR MOUNTED ON EACH OF SAID PEDESTALS, SAID ACTUATORS EACH OPERABLE TO ROTATE, DRIVE TO A PREDETERMINED DEPTH AND RETRACT A DRILL BIT MOUNTED THEREIN ON A BORING AXIS PARALLEL TO THE AXIS OF ITS RESPECTIVE MOUNTING PEDESTAL; LEG TEMPLATE MEANS REMOVABLY SECURED TO THE OUTER SURFACE OF SAID BOTTOM PLATE AND SUPPORTING FOUR LEG PEDESTALS HAVING THE SPATIAL AND ANGULAR RELATION OF THE LEGS FOR SAID CHAIR SEAT BLANK, EACH OF SAID LEG PEDESTALS SUPPORTING A PNEUMATIC DRILL ACTUATOR SIMILAR TO SAID ACTUATORS ON SAID BACK SPINDLE TEMPLATE; A TRANSVERSE CLAMPING BAR BETWEEN SAID TOP AND BOTTOM PLATES EXTENDING SUBSTANTIALLY THE WIDTH OF SAID SEAT BLANK; AN ACTUATOR ON SAID TOP PLATE COUPLED TO DRIVE SAID CLAMPING BAR TOWARD SAID BOTTOM PLATE AND POSITIONING SAID CLAMPING BAR TO AVOID INTERFERENCE WITH THE DRILL TRAVEL OF ANY HOLES BORED IN THE TOP SURFACE OF SAID SEAT BLANK; POSITIONING MEANS FOR LOCATING A SEAT BLANK IN PREDETERMINED POSITION BETWEEN SAID TOP AND BOTTOM PLATES OF SAID MASTER TEMPLATE; AND MEANS OPERABLE TO ENERGIZE SAID ACTUATOR TO CLAMP SAID SEAT BLANK SECURELY AGAINST THE INNER SURFACE OF SAID BOTTOM PLATE AND SUBSEQUENTLY ENERGIZE ALL OF SAID DRILL ACTUATORS TO BORE ALL OF THE HOLES IN THE TOP AND BOTTOM OF SAID SEAT BLANK, RETRACT SAID DRILLS AND FINALLY RETRACT SAID CLAMPING BAR TO PERMIT REMOVAL OF THE DRILLED SEAT BLANK. 